What’s available depends on uni. Older unis often have quite a bit of older accom. It is often catered and has shared bathrooms. But people still opt for those unis and those halls because the unis are often more prestigious and the original halls in the best locations. These things trump other stuff.
I agree that often those who can’t consider a shared bathroom either have additional needs or pretty limited life experience, which makes a shared bathroom impractical or sound v scary. Most people who share find it’s not actually a big deal. But if you’re a 17 year old thinking about it and not surprisingly lived at home, many will find the idea a bit daunting. Parental attitude plays a big role - if you think it sounds awful, they probably will too. I suspect families with a history of uni - most of wh will have had shared bathrooms 30+ years ago, are less phased by it.
Bear in mind that en-suites can add substantially to weekly cost and if the rent is more than 30 weeks a year, it can be thousands more.
The irony is that often those on full maintenance loans are more likely to pick the en-suites - without this, they might manage without a full loan or be able to pay some back at the end of their studies or need to work less as students without it.
My input into this, is that at unis with catered accom (proper catered provision in the halls - not a central hub) it’s hugely worth considering. These things benefits are enormous. Yes, you have to eat within a window of serving time, but the chance to mix more with more than just a flat of people and be forced out of your meal for good is a massive, underestimated benefit.
Lots of student self caters flats are fairly small. People can find great bonds but the chance ‘your people’ are in that 6 or 8 seems small. Too many reports of awkward flats and people cooking and taking their meal back to their room to eat don’t sound good at all. I know catered halls don’t get built so much today but that’s really about cost. If it’s available, it can be a massive benefit …but again young people can’t always see ahead to what those benefits might be.